The field of the invention is that of a circuit breaker for protecting an electrical circuit and the invention relates more particularly to small circuit breakers suited for automotive applications.
A known circuit breaker particularly adapted for use in a fuse-block-like component in automobiles for protecting various electrical circuits in the automobile has a pair of thin flat terminals embedded in a side wall of an electrically insulating housing so that respective broad flat sides of the terminals are exposed within the housing chamber in spaced side-by-side relation to each other. A thermostat metal member has one end welded to the exposed surface of one of the terminals to extend along the chamber wall and has a contact at its opposite end adapted to engage and disengage a mating contact on the broad exposed surface of the other terminal to open and close a circuit between the terminals in response to temperature changes in the member for protecting the circuit against current overloads. The circuit breaker structure is very compact and is adapted to carry heavy currents relative to its size making it very desirable for automotive circuit protection applications. However, the contact carried on the thermostat metal member preferably comprises a material such as a silver alloy to display low contact resistance. Such materials erode slowly over the service life of the device and can eventually stick or weld to the mating contact on the other terminal locking the circuit in closed position particularly after the silver alloy material has been substantially eroded away. It would be desirable if the circuit breaker could be adapted to open the circuit even in the event of contact welding to assure proper protection of the circuit. It would also be desirable to adapt the circuit heater to reduce contact wear and erosion.